During this century, the demand for petroleum as a source of energy and as a primary raw material for the petrochemical industry has resulted in an increase in world production from 29 to over 2,400 million metric tons per year. This dramatic increase in the production, refining and distribution of crude oil has also brought with it an ever-increasing problem of environmental pollution. In part, this has been a consequence of the massive movements of petroleum by oil tankers from the areas of high production to those of high consumption. It has been estimated that 0.5% (12 million metric tons per year) of transported crude oil finds its way into sea water, largely through accidental spills and deliberate discharge of ballast and wash waters from oil tankers.
The toxicity of crude and refined oil to the environment and, even more directly, to man is well documented (D. F. Boefsch et al., "Oil Spills and the Marine Environment", Ballinger Publ., Cambridge, 1974 114 pp.; A. Nelson-Smith in the collected papers edited by P. Hepple, "Water Pollution by Oil", Elsevier, N.Y., 1971, pp 273-80) and need not be discussed in detail. It is sufficient to state that crude oil contains mutagenic, carcinogenic and growth inhibiting chemicals and that even small quantities (5-100 mg per liter) of certain petroleum fractions destroy microalgae and juvenile forms of microorganisms. Furthermore, it has been reported (I. Chett et al., Nature 261, 308-9 (1976)) that petroleum inhibits microbial decomposition of organic matter in sea water by interfering with the ability of the microorganisms involved to move or orient themselves. Put simply, oil pollution in the ocean in general and in the coastal waters in particular presents a serious problem to commercial fisheries, recreational resources and public health.
Oil pollution is only one source among many which contaminate the environment. Environmental pollutants also include non-petroleum organic contaminants, which can be generated from various sources. Such organic and inorganic contaminants can be found in industrial waste produced by carpet and textile mills, pulp and paper mills, citrus processing plants, commercial kitchens, fast food restaurants, and food processing plants, for example. Such organic contaminants include pesticides, such as herbicides, growth inhibitors, growth regulators, sterilants, and the like.
Different approaches to reducing the concentration of environmental contaminants have been explored. One such approach is bioremediation, which is the use of living organisms to break down organic and inorganic contaminants into more basic components, remove environmental pollutants, restore contaminated sites, and prevent the accumulation of further pollutants. Generally, bioremediation is accomplished using bacteria, although other microorganisms, namely fungi and algae, have been used. See, for example, Ronald M. Atlas, Chemical & Engineering News, Apr. 3, 1995, pp. 32-42. There still exists a need, however, to reduce the amount of organic and inorganic contaminants in aquatic and terrestrial environments.